phosphonic acid

[SalemCastles]

Thanks...how would you safely get rid of it other than taking to the hazardous chemical depot?

[chem geek]

You mean the metal sequestrant product? I'd just follow the instructions on the label for disposal. If there are no instructions for disposal, then just put it into the trash. The MSDS for the phosphonate products I could find just say "Dispose of in accordance with all applicable local, state and federal regulations. Empty containers retain vapor or product residue and can be dangerous." On product labels, I couldn't find any disposal information.

HOWEVER, you might just need a metal sequestrant someday if for whatever reason you do get metal ions (copper or iron) into your water so you could just keep it around in a storage shed, just in case. Up to you.

Other environmental information is as follows -- it's far less toxic to aquatic organisms than chlorine, for example.
ENVIRONMENTAL TOXICITY:
Invertebrates: 48 h, EC50 Water flea (Daphnia magna) 527 mg/l
Fish: 96 h, LC50 Rainbow trout (Oncorhynchus mykiss) 368 mg/l
96 h, LC50 Bluegill sunfish (Lepomis macrochirus) 868 mg/l
Algae: 96 h, EC50 Algae (Selenastrum capricornutum) 3 mg/l
Algal growth inhibition is due to ability of this product to complex materials not to toxicity per se.
ENVIRONMENTAL FATE
BIODEGRADATION: Zahn-Wellens Dissolved Organic Carbon removed 33 % 28 d
Modified OECD Screening theoretical CO2 evolution 2 % 70 d
Modified SCAS Dissolved Organic Carbon removed 90 %
Closed Bottle BOD30/COD 5 %
Degrades after acclimatization
BIOCONCENTRATION FACTOR (BCF): Not expected to bioaccumulate.

[PoolDoc]

Chem_Geek gave you the 'right' answer.

Here's a simpler one that's not quite so compliant with all the 'rules': HEDP is not very toxic, but is pretty acidic if concentrated. Still, if you just flush it, and then flush again after, there shouldn't be any problems.

But, I'd keep it. Just store it out of sunlight and out of severe heat, so the bottle won't deteriorate.

Ben

[rcy100]

What a viscious circle the pool stores have going.

Every opening/closing kit that I've seen where I live has - Oxidizer, 40% algaecide and "stain and scale" remover (which is the phosphonic acid). So you use this stuff at least twice a year (my pool store recommended algaecide and the stain and scale remover ONCE A MONTH), then they test for phosphates (which are increasing because of the phosphonic acid) and sell you phosphate remover.

[waterbear]

What a viscious circle the pool stores have going.

Every opening/closing kit that I've seen where I live has - Oxidizer, 40% algaecide and "stain and scale" remover (which is the phosphonic acid). So you use this stuff at least twice a year (my pool store recommended algaecide and the stain and scale remover ONCE A MONTH), then they test for phosphates (which are increasing because of the phosphonic acid) and sell you phosphate remover.

NOW you are catching on!